I. Field of the Invention
The invention relates to a method for melting glass in one or several burner-heated tanks by preheating and feeding pellets formed of the batch to be molten into the tank by means of a gaseous medium under pressure. The invention relates also to a device for carrying out the method according to the invention.
II. Description of the Prior Art
According to conventional methods the batch or agglomeration to be molten and consisting essentially of sand, sodiumcarbonate, potassium, carbonate, lime, and magnesium oxide--either cold or preheated--is introduced into the glass melt at regular intervals of time or continuously. These methods have the drawback that the batch floating on the surface of the melt impedes the transfer of heat from the burners to the glass, which substantially delays the melting and refining process. The melting capacity of the furnace system used, including the tank and the attainable quality of the glass, depend, however, on the melting rate and the degree of refining.
On the other hand, the conventional arrangement of the heat sources or burners between the floating batch blanket and the crown of the furnace leads to extremely high temperatures in the upper part of the furnace and the crown. This in turn results in heavy corrosion of the refractory material of the furnace having not only a detrimental effect on the service life of the plant but also favoring the formation of glass defects. In addition, the high temperatures in the upper part of the furnace naturally lead to high heat losses and thus high energy consumption
Another known type of melting furnace is electrically heated providing the heat sources in the glass melt; this design does, however, not allow the use of burners. This electric melting process yields glass of high quality, but because of the high cost of electric energy it is used only for the manufacture of high-quality special glasses.
The object of the invention therefore is to provide a method of the kind outlined above being superior to conventional methods in particular in that it consumes substantially less energy and/or having a higher melting rate. It is another object of the invention to improve the quality of glass produced with burner-heated tanks.